Various technologies may allow a user to experience a mix of real and virtual worlds. For example, some display devices, such as various head-mounted display devices, may comprise see-through displays that allow superposition of displayed images over a real-world background environment. The images may appear in front of the real-world background environment when viewed through the see-through display. In particular, the images may be displayed on the see-through display such that they appear intermixed with elements in the real-world background environment in what may be referred to as augmented reality.